1. Field of the Invention
The present invention relates to tool for smoothing the joints of interior walls constructed of plaster board or drywall.
2. Description of the Prior Art
One extremely common form of construction of interior walls and ceilings uses plaster board or drywall wallboard. The wallboard joints between two adjacent wallboards are commonly "taped" so that they are not noticeable.
The taping of wallboard joints has in the past been a relatively complicated, time consuming, messy, and often frustrating procedure, particularly for persons who are constructing interior walls and ceilings on a `do it yourself` basis. The traditional method of smoothing taped joints involves the applying three coats of wallboard joint compound, which is commercially available in both ready-mixed and powder form. In the case of its powder form, the wallboard joint compound powder is mixed with water to form a paste.
The first step of taping a wallboard joint involves applying a thick layer of joint compound which completely fills the seam formed by the two abutting wallboard sheets.
The next step is to embed wallboard tape into the thick layer of joint compound. The wallboard tape is a perforated paper tape having a width of about two inches, and which is normally sold in rolls. The tape is centered over the length of the seam and is pressed into the thick first layer of joint compound so that the compound oozes through the perforations of the tape. A wallboard knife is usually used to press the tape into the first layer of joint compound.
After the first layer of joint compound (with embedded tape) has dried, it is usually sanded smooth with dry sandpaper wrapped around a sanding block. This sanding step is particularly necessary if the surface of the first layer of joint compound is rough.
A second thin layer of joint compound is then applied over the first layer of joint compound and the wallboard tape. This second layer joint compound is wider (generally about 6 to 8 inches) than the first layer.
After the second layer has dried, sanding of the second layer is once again performed to smooth the joint. A third thin layer of joint compound is then applied over the second layer. This third layer is feathered out to about 12 to 14 inches from the center of the joint.
When the third coat of joint compound is thoroughly dry, it is sanded with a dry medium sandpaper. Once the surface of the wallboard joint is smooth and even, a primer coat is applied.
In the past, smoothing wallboard tape joints has been the messiest step in building an interior room. The residual dust that is formed by sanding makes a mess and is difficult to clean up.
The dust from sanding often becomes airborne, which spreads the dust further, and makes working in the room unpleasant. In addition, if water drips on the dust it forms cement which must be scraped up.
There has been a continuing need for an improved method of smoothing wallboard tape joints which is easier and less messy than the conventional prior art methods.